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- Title
Bryophyte-cyanobacterial associations as a key factor in N-fixation across the Canadian Arctic.
- Authors
Stewart, Katherine; Lamb, Eric; Coxson, Darwyn; Siciliano, Steven
- Abstract
Nitrogen inputs via biological N-fixation are important in arctic environments where N often limits plant productivity. An understanding of the direct and indirect theoretical causal relationships between key intercorrelated variables that drive the process of N-fixation is essential to understanding N input. An exploratory multi-group Structural Equation Modeling (SEM) approach was used to examine the direct and indirect effects of soil moisture, plant community functional composition, and bryophyte and lichen abundance on rates of nitrogen fixation at a low arctic ecosystem, two high arctic oases and a high arctic polar desert in the Canadian Arctic. Increasing soil moisture was strongly associated with an increasing presence of bryophytes and increasing bryophyte abundance was a major factor determining higher N-fixation rates at all sites. Shrubs had a negative effect on bryophyte abundance at all sites with the exception of the polar desert site at Alexandra Fjord highland. The importance of competition from vascular plants appears to be greater in more productive sites and may increase at lower latitudes. Moisture availability may have an indirect effect on ecosystem development by affecting N input into the system with bryophyte-cyanobacterial associations playing an important intermediary role in the process.
- Subjects
NORTHERN Canada; NITROGEN fixation; BRYOPHYTES; CYANOBACTERIA; STRUCTURAL equation modeling
- Publication
Plant & Soil, 2011, Vol 344, Issue 1/2, p335
- ISSN
0032-079X
- Publication type
Article
- DOI
10.1007/s11104-011-0750-x